Laser-tissue interaction studies were performed to help define specific characteristics of laser sources which would be important for future animal and human investigations examining the feasibility of laser angioplasty. Fresh human cadaver coronary arteries were exposed to different lasers and differing lasing parameters and were studied employing a uniform methodology incorporating histology, ocular micrometry, fast-reactive mechanical thermocouples on the adventitia, and fast infrared surface thermography. This work has helped to delineate the tissue thermal injury patterns and ablative efficacy of various laser sources in air and will have major implication in deciding the proper specifications for a laser catheter system to be used in subsequent in vivo investigations.